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Use strncasecmp instead of strncmp when comparing the password scheme.
This change could theoretically affect some people who actually have one
of the scheme's in lower case in their password, but this is extremely
unlikely in the real world.

Pointed out by David Diggles (david <at> elven <dot> com <dot> au)
OK sthen@

/*	$OpenBSD: auth.c,v 1.15 2022/06/29 09:10:13 martijn Exp $ */

/*
 * Copyright (c) 2009, 2010 Martin Hedenfalk <martin@bzero.se>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/queue.h>
#include <netinet/in.h>

#include <errno.h>
#include <openssl/sha.h>
#include <pwd.h>
#include <resolv.h>		/* for b64_pton */
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "ldapd.h"
#include "log.h"

static int
aci_matches(struct aci *aci, struct conn *conn, struct namespace *ns,
    char *dn, int rights, char *attr, enum scope scope)
{
	struct btval	 key;

	if ((rights & aci->rights) != rights)
		return 0;

	if (dn == NULL)
		return 0;

	if (aci->target != NULL) {
		key.size = strlen(dn);
		key.data = dn;

		if (scope == LDAP_SCOPE_BASE) {
			switch (aci->scope) {
			case LDAP_SCOPE_BASE:
				if (strcmp(dn, aci->target) != 0)
					return 0;
				break;
			case LDAP_SCOPE_ONELEVEL:
				if (!is_child_of(&key, aci->target))
					return 0;
				break;
			case LDAP_SCOPE_SUBTREE:
				if (!has_suffix(&key, aci->target))
					return 0;
				break;
			}
		} else if (scope == LDAP_SCOPE_ONELEVEL) {
			switch (aci->scope) {
			case LDAP_SCOPE_BASE:
				return 0;
			case LDAP_SCOPE_ONELEVEL:
				if (strcmp(dn, aci->target) != 0)
					return 0;
				break;
			case LDAP_SCOPE_SUBTREE:
				if (!has_suffix(&key, aci->target))
					return 0;
				break;
			}
		} else if (scope == LDAP_SCOPE_SUBTREE) {
			switch (aci->scope) {
			case LDAP_SCOPE_BASE:
			case LDAP_SCOPE_ONELEVEL:
				return 0;
			case LDAP_SCOPE_SUBTREE:
				if (!has_suffix(&key, aci->target))
					return 0;
				break;
			}
		}
	}

	if (aci->subject != NULL) {
		if (conn->binddn == NULL)
			return 0;
		if (strcmp(aci->subject, "@") == 0) {
			if (strcmp(dn, conn->binddn) != 0)
				return 0;
		} else if (strcmp(aci->subject, conn->binddn) != 0)
			return 0;
	}

	if (aci->attribute != NULL) {
		if (attr == NULL)
			return 0;
		if (strcasecmp(aci->attribute, attr) != 0)
			return 0;
	}

	return 1;
}

/* Returns true (1) if conn is authorized for op on dn in namespace.
 */
int
authorized(struct conn *conn, struct namespace *ns, int rights, char *dn,
    char *attr, int scope)
{
	struct aci	*aci;
	int		 type = ACI_ALLOW;

	/* Root DN is always allowed. */
	if (conn->binddn != NULL) {
		if (conf->rootdn != NULL &&
		    strcasecmp(conn->binddn, conf->rootdn) == 0)
			return 1;
		if (ns != NULL && ns->rootdn != NULL &&
		    strcasecmp(conn->binddn, ns->rootdn) == 0)
			return 1;
	}

	/* Default to deny for write access. */
	if ((rights & (ACI_WRITE | ACI_CREATE)) != 0)
		type = ACI_DENY;

	log_debug("requesting %02X access to %s%s%s by %s, in namespace %s",
	    rights,
	    dn ? dn : "any",
	    attr ? " attribute " : "",
	    attr ? attr : "",
	    conn->binddn ? conn->binddn : "any",
	    ns ? ns->suffix : "global");

	SIMPLEQ_FOREACH(aci, &conf->acl, entry) {
		if (aci_matches(aci, conn, ns, dn, rights,
		    attr, scope)) {
			type = aci->type;
			log_debug("%s by: %s %02X access to %s%s%s by %s",
			    type == ACI_ALLOW ? "allowed" : "denied",
			    aci->type == ACI_ALLOW ? "allow" : "deny",
			    aci->rights,
			    aci->target ? aci->target : "any",
			    aci->attribute ? " attribute " : "",
			    aci->attribute ? aci->attribute : "",
			    aci->subject ? aci->subject : "any");
		}
	}

	if (ns != NULL) {
		SIMPLEQ_FOREACH(aci, &ns->acl, entry) {
			if (aci_matches(aci, conn, ns, dn, rights,
			    attr, scope)) {
				type = aci->type;
				log_debug("%s by: %s %02X access to %s%s%s by %s",
				    type == ACI_ALLOW ? "allowed" : "denied",
				    aci->type == ACI_ALLOW ? "allow" : "deny",
				    aci->rights,
				    aci->target ? aci->target : "any",
				    aci->attribute ? " attribute " : "",
				    aci->attribute ? aci->attribute : "",
				    aci->subject ? aci->subject : "any");
			}
		}
	}

	return type == ACI_ALLOW ? 1 : 0;
}

static int
send_auth_request(struct request *req, const char *username,
    const char *password)
{
	struct auth_req	 auth_req;

	memset(&auth_req, 0, sizeof(auth_req));
	if (strlcpy(auth_req.name, username,
	    sizeof(auth_req.name)) >= sizeof(auth_req.name))
		goto fail;
	if (strlcpy(auth_req.password, password,
	    sizeof(auth_req.password)) >= sizeof(auth_req.password))
		goto fail;
	auth_req.fd = req->conn->fd;
	auth_req.msgid = req->msgid;

	if (imsgev_compose(iev_ldapd, IMSG_LDAPD_AUTH, 0, 0, -1, &auth_req,
	    sizeof(auth_req)) == -1)
		goto fail;

	req->conn->bind_req = req;
	return 0;

fail:
	memset(&auth_req, 0, sizeof(auth_req));
	return -1;
}

/*
 * Check password. Returns 1 if password matches, 2 if password matching
 * is in progress, 0 on mismatch and -1 on error.
 */
static int
check_password(struct request *req, const char *stored_passwd,
    const char *passwd)
{
	unsigned char	 tmp[128];
	unsigned char	 md[SHA_DIGEST_LENGTH];
	char		*encpw;
	unsigned char	*salt;
	SHA_CTX		 ctx;
	int		 sz;

	if (stored_passwd == NULL)
		return -1;

	if (strncasecmp(stored_passwd, "{SHA}", 5) == 0) {
		sz = b64_pton(stored_passwd + 5, tmp, sizeof(tmp));
		if (sz != SHA_DIGEST_LENGTH)
			return (-1);
		SHA1_Init(&ctx);
		SHA1_Update(&ctx, passwd, strlen(passwd));
		SHA1_Final(md, &ctx);
		return (bcmp(md, tmp, SHA_DIGEST_LENGTH) == 0 ? 1 : 0);
	} else if (strncasecmp(stored_passwd, "{SSHA}", 6) == 0) {
		sz = b64_pton(stored_passwd + 6, tmp, sizeof(tmp));
		if (sz <= SHA_DIGEST_LENGTH)
			return (-1);
		salt = tmp + SHA_DIGEST_LENGTH;
		SHA1_Init(&ctx);
		SHA1_Update(&ctx, passwd, strlen(passwd));
		SHA1_Update(&ctx, salt, sz - SHA_DIGEST_LENGTH);
		SHA1_Final(md, &ctx);
		return (bcmp(md, tmp, SHA_DIGEST_LENGTH) == 0 ? 1 : 0);
	} else if (strncasecmp(stored_passwd, "{CRYPT}", 7) == 0) {
		encpw = crypt(passwd, stored_passwd + 7);
		if (encpw == NULL)
			return (-1);
		return (strcmp(encpw, stored_passwd + 7) == 0 ? 1 : 0);
	} else if (strncasecmp(stored_passwd, "{BSDAUTH}", 9) == 0) {
		if (send_auth_request(req, stored_passwd + 9, passwd) == -1)
			return (-1);
		return 2;	/* Operation in progress. */
	} else
		return (strcmp(stored_passwd, passwd) == 0 ? 1 : 0);
}

static int
ldap_auth_sasl(struct request *req, char *binddn, struct ber_element *params)
{
	char			*method;
	char			*authzid, *authcid, *password;
	char			*creds;
	size_t			 len;

	if (ober_scanf_elements(params, "{sx", &method, &creds, &len) != 0)
		return LDAP_PROTOCOL_ERROR;

	if (strcmp(method, "PLAIN") != 0)
		return LDAP_STRONG_AUTH_NOT_SUPPORTED;

	if ((req->conn->s_flags & F_SECURE) == 0) {
		log_info("refusing plain sasl bind on insecure connection");
		return LDAP_CONFIDENTIALITY_REQUIRED;
	}

	authzid = creds;
	authcid = memchr(creds, '\0', len);
	if (authcid == NULL || authcid + 2 >= creds + len)
		return LDAP_PROTOCOL_ERROR;
	authcid++;
	password = memchr(authcid, '\0', len - (authcid - creds));
	if (password == NULL || password + 2 >= creds + len)
		return LDAP_PROTOCOL_ERROR;
	password++;

	log_debug("sasl authorization id = [%s]", authzid);
	log_debug("sasl authentication id = [%s]", authcid);

	if (send_auth_request(req, authcid, password) != 0)
		return LDAP_OPERATIONS_ERROR;

	free(req->conn->binddn);
	req->conn->binddn = NULL;
	if ((req->conn->pending_binddn = strdup(authcid)) == NULL)
		return LDAP_OTHER;

	return LDAP_SUCCESS;
}

static int
ldap_auth_simple(struct request *req, char *binddn, struct ber_element *auth)
{
	int			 pwret = 0;
	char			*password;
	char			*user_password;
	struct namespace	*ns;
	struct ber_element	*elm = NULL, *pw = NULL;

	if (*binddn == '\0') {
		free(req->conn->binddn);		/* anonymous bind */
		req->conn->binddn = NULL;
		log_debug("anonymous bind");
		return LDAP_SUCCESS;
	}

	if ((req->conn->s_flags & F_SECURE) == 0) {
		log_info("refusing non-anonymous bind on insecure connection");
		return LDAP_CONFIDENTIALITY_REQUIRED;
	}

	if (ober_scanf_elements(auth, "s", &password) != 0)
		return LDAP_PROTOCOL_ERROR;

	if (*password == '\0') {
		/* Unauthenticated Authentication Mechanism of Simple Bind */
		log_debug("refusing unauthenticated bind");
		return LDAP_UNWILLING_TO_PERFORM;
	}

	if (conf->rootdn != NULL && strcmp(conf->rootdn, binddn) == 0) {
		pwret = check_password(req, conf->rootpw, password);
	} else if ((ns = namespace_lookup_base(binddn, 1)) == NULL) {
		return LDAP_INVALID_CREDENTIALS;
	} else if (ns->rootdn != NULL && strcmp(ns->rootdn, binddn) == 0) {
		pwret = check_password(req, ns->rootpw, password);
	} else if (namespace_has_referrals(ns)) {
		return LDAP_INVALID_CREDENTIALS;
	} else {
		if (!authorized(req->conn, ns, ACI_BIND, binddn,
		    NULL, LDAP_SCOPE_BASE))
			return LDAP_INSUFFICIENT_ACCESS;

		elm = namespace_get(ns, binddn);
		if (elm == NULL && errno == ESTALE) {
			if (namespace_queue_request(ns, req) != 0)
				return LDAP_BUSY;
			return -1;	/* Database is being reopened. */
		}

		if (elm != NULL)
			pw = ldap_get_attribute(elm, "userPassword");
		if (pw != NULL) {
			for (elm = pw->be_next->be_sub; elm;
			    elm = elm->be_next) {
				if (ober_get_string(elm, &user_password) != 0)
					continue;
				pwret = check_password(req, user_password, password);
				if (pwret >= 1)
					break;
			}
		}
	}

	free(req->conn->binddn);
	req->conn->binddn = NULL;

	if (pwret == 1) {
		if ((req->conn->binddn = strdup(binddn)) == NULL)
			return LDAP_OTHER;
		log_debug("successfully authenticated as %s",
		    req->conn->binddn);
		return LDAP_SUCCESS;
	} else if (pwret == 2) {
		if ((req->conn->pending_binddn = strdup(binddn)) == NULL)
			return LDAP_OTHER;
		return -LDAP_SASL_BIND_IN_PROGRESS;
	} else if (pwret == 0)
		return LDAP_INVALID_CREDENTIALS;
	else
		return LDAP_OPERATIONS_ERROR;
}

void
ldap_bind_continue(struct conn *conn, int ok)
{
	int			 rc;

	if (ok) {
		rc = LDAP_SUCCESS;
		conn->binddn = conn->pending_binddn;
		log_debug("successfully authenticated as %s", conn->binddn);
	} else {
		rc = LDAP_INVALID_CREDENTIALS;
		free(conn->pending_binddn);
	}
	conn->pending_binddn = NULL;

	ldap_respond(conn->bind_req, rc);
	conn->bind_req = NULL;
}

int
ldap_bind(struct request *req)
{
	int			 rc = LDAP_OTHER;
	long long		 ver;
	char			*binddn;
	struct ber_element	*auth;

	++stats.req_bind;

	if (ober_scanf_elements(req->op, "{ise", &ver, &binddn, &auth) != 0) {
		rc = LDAP_PROTOCOL_ERROR;
		goto done;
	}

	if (req->conn->bind_req) {
		log_debug("aborting bind in progress with msgid %lld",
		    req->conn->bind_req->msgid);
		request_free(req->conn->bind_req);
		req->conn->bind_req = NULL;
	}

	normalize_dn(binddn);
	log_debug("bind dn = %s", binddn);

	switch (auth->be_type) {
	case LDAP_AUTH_SIMPLE:
		if ((rc = ldap_auth_simple(req, binddn, auth)) < 0)
			return rc;
		break;
	case LDAP_AUTH_SASL:
		if ((rc = ldap_auth_sasl(req, binddn, auth)) == LDAP_SUCCESS)
			return LDAP_SUCCESS;
		break;
	default:
		rc = LDAP_STRONG_AUTH_NOT_SUPPORTED;
		break;
	}

done:
	return ldap_respond(req, rc);
}